The present invention relates to portable power planers and in particular to an improved cutterhead assembly for a power planer.
In general, portable power planers include a motor driven rotary cutterhead having one or more blade retaining or pressure plate assemblies which are operative to retain cutting blades for rotation with the cutterhead to engage and perform a cutting operation upon the surface of a workpiece. Such cutting blades are made in standard sizes of predetermined dimensions and are adapted to be assembled with such pressure plate assemblies. Prior known cutterhead assemblies have required means for adjusting the elevation of either the cutting blade or the pressure plate assembly relative to the cutterhead so that the cutting edge of the blade projects beyond the cutting circle of the cutterhead the distance required for performing a proper cutting operation. Such prior cutterhead assemblies have also required clamping means for clamping either the cutting blade or the pressure plate to the body of the cutterhead to prevent radial ejection of the blade or blade-pressure plate assembly during use of these power planer devices.
The need for an operator to make adjustments in the elevation of the cutting blades for efficient operation of such prior devices results in an inconvenience for the operator during installation, reversal or replacement of cutting blades. Moreover, the elevation adjusting means and clamping means for such prior power planer devices have generally been provided in the form of bolts or screws which, of necessity, must be turned and adjusted by the operator to effect efficient and safe operation of such devices. Due to space limitations, the size and placement of these bolts or screws often makes such adjustments time consuming and tedious. Furthermore, an operator can occasionally forget to make these adjustments, which can result in these devices operating inefficiently or improperly. Additionally, such prior devices are of a generally complicated configuration and require the component parts of the cutterhead assembly to be manufactured to fairly close tolerances.
It is therefore an object of the present invention to provide a cutterhead assembly which can receive cutting blades of standard and predetermined dimensions without requiring an operator to make adjustments on the cutterhead when replacing or reversing the cutting blade in order to position the cutting blade in elevation so that the cutting edge thereof projects beyond the cutting circle of the cutterhead the desired proper distance.
It is a further object of the present invention to provide such a cutterhead assembly wherein the cutting blade is retained against radial ejection from the assembly during operation of the power planer even absent the exertion of a clamping force to hold the blade in fixed relation to the cutterhead.
It is an additional object of the present invention to provide such a cutterhead assembly which is of a simplified and less costly configuration, and which can accommodate tolerance variations which occur during the manufacture of the respective parts to reduce the manufacturing costs thereof.
Also, it is an object of the present invention to provide such a cutterhead assembly which enables the assembly to be easily serviced, and cutting blades to be simply and efficiently installed, reversed and replaced.
The cutterhead assembly according to the present invention includes an elongated core and a pressure plate which is permanently assembled with the core. The pressure plate is assembled with the core by a pair of bolts which extend through apertures in the pressure plate and into threaded bores in the core. When assembled with the core, the pressure plate includes a cantilevered portion which cooperates with a face of the core to define a longitudinally extending blade receiving slot for receiving blades of a standard configuration. The apertures in the pressure plate are formed to define laterally elongated openings which allow the pressure plate to be moved relative to the core prior to assembly therewith for properly defining the blade receiving slot. This feature provides a cutterhead assembly which can accommodate tolerance variations occurring during the manufacture of the core and the pressure plate. To properly align the pressure plate relative to the core, these pieces are placed in a jig or fixing machine with a standard cutting blade and the pressure plate is positioned on the core to place the cutting blade in its preferred position with respect to the cutting circle of the cutterhead assembly. The pressure plate can thereafter be fixed in its chosen location relative to the core by tightening the previous described bolts.
Cutting blades for the assembly can be installed by longitudinally inserting them into the blade receiving slot from one end of the assembly. The assembly includes a cover portion which is assembled with the core and pressure plate by a series of clamping bolts extending through the cover portion, a second set of elongated apertures in the pressure plate, and into threaded bores in the core. When the clamping bolts are tightened, the cover portion will clampingly load the cantilevered portion of the pressure plate, enabling it to cooperate with the core to clampingly retain the cutting blade in the blade receiving slot. The cantilevered portion of the pressure plate includes a longitudinally extending projection which extends into the blade receiving slot and is adapted to engage a generally complementary-shaped recess extending longitudinally along one face of the cutting blade. This projection is preferably of sufficient height to prevent radial ejection of the cutting blade in the event an operator neglects to tighten the clamping bolts on the cover portion.
Additional objects and advantages of the present invention will become apparent from a reading of the detailed description of the preferred embodiment which makes reference to the following set of drawings in which :